My invention relates to a control circuit for a radio transceiver or the like, and particularly to such a control circuit that prevents the radio transceiver from being inadvertently turned off during operation by the user opening a vehicular ignition switch or a transceiver on-off switch.
Prior art radio transceivers presently used in mobile vehicles, particularly automobiles, are powered by the vehicular ignition switch. When the ignition switch is in the on or accessory position, the transceiver can be powered. In addition a transceiver on-off switch is placed in series between the ignition switch and the transceiver so that the transceiver can be turned off even though the ignition switch is on, and so that the transceiver will be turned off when the ignition switch is off, so as to prevent discharging the vehicular battery if a user leaves the on-off switch in the on position.
However, the status or position of the ignition switch creates a problem in the radio transceivers which use some form of automatic or program control to establish and maintain a call. This is particularly true in mobile telephone or cellular transceivers. For example, if the vehicle stalls and requires restarting, or if the user has reached his destination and turned the ignition switch off, the program controlled radio connection will be broken. As a result, the user's conversation with the distant base station or telephone station will be lost, since the transceiver was turned off by the ignition switch. Relatively simple transceivers that do not require an automatic or program control technique, such as crystal controlled or frequency synthesized push-to-talk transceivers, do not have this problem, since the call can be restored by simply turning the radio back on. However, the automatic or program type of radio control will result in a call being lost since the program must be re-established or reinitiated from the beginning once the transceiver is turned back on. In addition, relevant data or information, such as the channel number being used, the loop tone frequency being used, the power level setting being used, and other information are lost. Furthermore, re-establishing a call can result in additional billing charges.
Accordingly, there is a definite need for some arrangement or feature which maintains a vehicular transceiver in the on or operating condition despite the vehicular ignition switch or the transceiver on-off switch inadvertently or intentionally being turned off.